CVE-2026-44486: Axios Node.js Proxy Credential Leakage Vulnerability

Technical summary

The vulnerability stems from improper header lifecycle management in Axios' Node.js HTTP adapter. When the library forwards a request through an authenticated proxy, it adds a Proxy-Authorization header for proxy server authentication. Upon receiving a redirect response (3xx status code), Axios processes the redirect and sends the new request to the target URL. However, if the redirect destination exists outside the authenticated proxy path—such as a direct internet host or a different proxy—Axios does not strip the stale Proxy-Authorization header. Consequently, the proxy credentials are transmitted to an untrusted endpoint in cleartext or via the redirected HTTPS connection, creating a credential exposure vector. This issue arises from the adapter's failure to validate proxy applicability after redirect processing.

Business impact

Proxy credentials leaked to malicious redirect targets can be exploited by attackers to authenticate requests directly to your organization's proxy infrastructure, potentially enabling reconnaissance, lateral movement, or bypassing proxy-enforced security controls. For enterprises relying on authenticated proxies for egress filtering, DLP, or threat detection, credential compromise represents a significant control evasion risk. Applications processing sensitive data (API requests with authentication, internal service calls) routed through proxies face confidentiality risks if redirect chains are controlled by attackers. The impact is amplified in environments where proxy credentials are shared across teams or service accounts.

Affected systems

Node.js applications using Axios versions prior to 0.32.0 (for the 0.x release line) or prior to 1.16.0 (for the 1.x release line) are vulnerable. The vulnerability requires concurrent conditions: Axios must be configured with an authenticated HTTP or HTTPS proxy, automatic redirect following must be enabled (the default behavior), and a redirect response must originate from a source an attacker controls or influences. Browser-based Axios implementations are not affected because browsers enforce their own same-origin redirect policies and do not expose proxy authentication mechanisms to JavaScript.

Exploitability

Exploitability is moderate to high in specific contexts. An attacker must control or influence a redirect chain: for example, hosting a malicious web server that returns a 301/302 redirect, or compromising a legitimate server to inject redirects. Once a victim application follows that redirect, the proxy credentials are leaked in the HTTP request headers visible to the redirect target. No user interaction is required beyond the application making the initial request. However, exploitation requires that the application: (1) uses an authenticated proxy, (2) actually encounters a redirect to an attacker-controlled or attacker-influenced destination, and (3) does not validate redirect targets. In typical deployments, not all outbound requests will be redirected, limiting the practical attack surface. Nonetheless, the CVSS 7.5 (HIGH) scoring reflects the ease of triggering the condition and the severity of confidential information disclosure.

Remediation

Upgrade Axios to version 0.32.0 or later (0.x line) or version 1.16.0 or later (1.x line). These versions implement proper header sanitization, ensuring Proxy-Authorization headers are removed or revalidated when a redirect target no longer requires proxy routing. Confirm your package.json or lock file reflects the patched version and run dependency checks to catch transitive Axios dependencies. Organizations unable to patch immediately should disable automatic redirects (set maxRedirects: 0) in Axios configuration, although this may break legitimate use cases requiring redirect following.

Patch guidance

Update Axios via npm/yarn: 'npm update axios' or 'yarn upgrade axios'. Verify the installed version matches 0.32.0+ or 1.16.0+ using 'npm list axios'. If Axios is a transitive dependency, identify the parent package and update it to a version that bundles the patched Axios release; consult the vendor advisory for the upstream package. Test your application thoroughly, as disabling or altering redirect behavior can affect legitimate third-party integrations. Pin Axios to the specific patched version to prevent accidental downgrades. Review any custom proxy configurations to ensure they align with the updated adapter behavior.

Detection guidance

In Node.js application logs, monitor for unusual Proxy-Authorization header values being transmitted to external hosts or non-proxy destinations; this may appear in HTTP client debug logs or network traces. Inspect network traffic from your application to identify Proxy-Authorization headers sent to servers outside your proxy infrastructure. Web application firewalls or egress proxies can detect outbound requests containing proxy credentials to unexpected targets. Correlate application dependencies against Axios version inventory; compare against the patched versions (0.32.0, 1.16.0) to identify vulnerable deployments. Code review of redirect handling or proxy configuration may reveal implicit redirect following combined with authenticated proxy setup.

Why prioritize this

Although the CVSS score is HIGH and the vulnerability is not yet widely weaponized (no KEV listing), the exploitability depends on specific architectural conditions (authenticated proxy + redirect). Prioritization should be based on: (1) whether your Node.js applications actually use authenticated proxies (many do for egress control or inspection); (2) whether those applications handle external or user-supplied URLs that could redirect; and (3) the sensitivity of proxy credentials in your environment. Teams running microservices or making outbound API calls through proxies should treat this as a near-term patch priority. Teams without authenticated proxy deployments can defer slightly but should still address within a standard patch cycle.

Risk score, explained

CVSS 3.1 score of 7.5 (HIGH) reflects: Attack Vector = Network (AV:N, exploitable remotely without local access), Attack Complexity = Low (AC:L, no special conditions required beyond redirect occurrence), Privileges Required = None (PR:N, no prior authentication needed), User Interaction = None (UI:N, automatic), Scope = Unchanged (S:U), Confidentiality = High (C:H, proxy credentials are confidential), Integrity = None (I:N, no data modification), Availability = None (A:N, no service disruption). The confidentiality impact is substantial due to the exposure of proxy credentials, which are typically treated as sensitive. The ease of triggering a redirect condition (if an attacker controls a target) elevates the score beyond medium.

Frequently asked questions